1. Field of the Invention
The present invention relates to an operation state display apparatus for displaying the operation state of a controlled object.
2. Description of the Prior Art
Heretofore, in sequential control equipment for repeating certain controls in a predetermined order for each constant period, it has been quite hard to find the state of work for a machine during one operation step or the order and course of the ON state or the OFF state of control elements such as a limit switch, a solenoid valve, etc. from one operation initiation time to the present. Accordingly, the maintenance of the control system has been difficult if the operation is stopped by certain abnormal operations of the controlled object.
If it is possible to find the information of reference operation of the controlled object and the information of operation from the operation step initiation to the present by certain means when an abnormal operation is caused, the abnormal operation of the machine can be found at an early stage by comparing both of the informations whereby the machine can be stopped before serious damage of the controlled object, the cause of the abnormal operation can be detected, and a repair of the normal operation of the machine can be made at an early stage to increase the operation rate of the machine.